Apparatus for fabrication of miniature structures

ABSTRACT

An apparatus is provided for fabrication of miniature structures which includes a substrate, a controllable energetic beam, a deposition layer supported on a material carrier element and a control unit operating the apparatus in either of “material removal” and “material transfer” modes of operation. In the “material removal” mode of operation, the control unit displaces the material carrier element away from an interception path with the energetic beam so that the energetic beam impinges in patterned fashion onto the surface of the substrate and disintegrates the surface material of the substrate. In the “material transfer” mode of operation, the control unit displaces the deposition layer to intercept with the energetic beam so that the material contained in the deposition layer is transferred and deposited on the surface of the substrate in a patterned fashion.

REFERENCE TO RELATED APPLICATIONS

This utility Patent Application is based on U.S. Provisional Applicationfor Patent (Serial No. 60/135,486) filed on May 24, 1999, and PCTApplication Serial No. PCT/US00/09817.

FIELD OF THE INVENTION

The present invention relates to an apparatus and technique forfabrication of a variety of miniature structures such as semiconductorchips, optical, chemical, biological, environmental, physical,electromagnetic detectors/sensors, mechanical and electromechanicalelements and actuators, antennae, different electronic components, aswell as vias, channels, guides, etc.

More particularly, the present invention relates to an apparatus andtechnique for fabrication of miniature structures where the Direct Write(additive process) and micromachining (subtractive process) are carriedout with and in the same fabrication tool by means of synchronouscontrol and manipulation of elements of the fabrication tool.

Still further, the present invention relates to an apparatus having acontrol mechanism which operates the fabrication apparatus in either oftwo modes of operation: “material transfer” and/or “material removal”modes of operation. The additive process, such as Laser ForwardTransfer, or Laser Induced Forward Transfer methodologies are carriedout during the “material transfer” mode of operation to depositmaterials on the substrate surface and to create additive structuressuch as various detectors, sensors, actuators, semiconductor chips, etc.In the “material removal” mode of operation a subtractive process iscarried out resulting in a material removal from the workpiece by meansof ablation, evaporation, melting, cutting, drilling, etc. of theworkpiece, thus creating channels, guides, vias. During the “materialremoval” mode of operation, the fabrication tool performs as amicromachining workstation so that the substrate with the structurespreviously created thereon during the “material transfer” mode ofoperation may be diced or excised into individual subunits, and can betrimmed or shaped to precise specified values.

Further, the present invention relates to an apparatus and method inwhich a controllable energy or energetic beam is directed towards asubstrate where a material carrier element having a deposition layerformed thereon is displaceably positioned in spaced relationship withthe substrate. A control unit synchronously manipulates the materialcarrier element and the energy beam in accordance with the type of thestructure to be manufactured.

In this manner, in a “material removal” mode of operation, the controlunit displaces the material carrier element away from interception withthe energy beam so that the energy beam impinges onto the surface of thesubstrate in a predetermined manner and disintegrates the surfacematerial of the substrate to a predetermined depth.

Further, in the “material transfer” mode of operation, the controlmechanism displaces the material carrier element into a positionintercepting the energy beam so that the energy beam modifies thedeposition layer on the material carrier element, and causes transferand deposition of the deposition material onto the surface of thesubstrate in accordance with a predetermined pattern.

In both modes of operation, for performing patterned removal of thematerial from the surface of the substrate or patterned deposition ofthe material onto the surface of the substrate, the control unit changesthe relative position between the energy beam and the substrate in apatterned manner.

BACKGROUND OF THE INVENTION

Miniature structures having electrical components are widely used in avariety of consumer and industrial items, such as TV sets, radios, cars,kitchen appliances, computers, etc.

Due to the need for such miniature structures, such as computer chips,and other mechanical and electromechanical elements, differentmanufacturing processes have been developed.

Methodologies of manufacture include, among others, additive DirectWrite processes such as Laser Forward Transfer (LFT), Matrix AssistantPulse Laser Evaporation, or Laser Induced Forward Transfer (LIFT)techniques, well-known to those proficient in the miniature structurefabrication art.

In the course of these techniques, a material from the depositionmaterial source is transferred towards a substrate and is depositedthereon in accordance with a predetermined pattern either to manufacturea single structure or a plurality of structures on the same substrate.Simultaneously, a subtractive process is employed using laser energy toablate, evaporate, melt, cut, drill, or otherwise remove material fromthe workpiece. In this manner, channels, guides, or vias can be lasermilled or drilled. Additionally, a substrate with a plurality ofstructures may be excised into individual subunits, trimmed or shaped.

Although both additive and subtractive processes are well-developed andknown in the miniature structures manufacturing industry, there is adrawback which still exists resulting from the necessity to transfer thesubstrate with deposited structures thereon from one area (where theadditive Direct Write process takes place) to a micromachiningworkstation, or conversely, from a micromachining station where thesurface cleaning takes place to a material deposition area.

During this substrate transfer from one location to another, physicaldamage to the workpiece may be found, the workpiece may be contaminated,or areas exposed during surface cleaning may be reoxidized, thussubstantially reducing yield of the high quality devices.

Additionally, transfer of the workpiece from one location to anotherrequires additional labor effort and precaution to protect the workpiecefrom being damaged or polluted, thus further increasing the costs andcomplexity of the manufacturing process and equipment.

Accordingly, despite the use of the existing manufacturing equipment andtechniques for fabrication of miniature structures, a long felt need hasarisen and exists for equipment and techniques free of the disadvantagesof the prior art.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a tool andmethod for fabrication of miniature structures which carry out bothadditive and subtractive processes in and with the same apparatus.

It is a further object of the present invention to provide an apparatusfor fabrication of miniature structures in which a control unit operatesthe apparatus in either a “material removal” and/or “material transfer”mode of operation. In this manner by using the same apparatus, either adeposition of a material on the surface of the substrate can be effectedor removal of the material from the surface of the substrate can beperformed.

It is an object of the present invention to provide an apparatus formanufacturing of miniature structures in which during a “materialremoval” mode of operation, the control unit permits direct impingementof the energy beam onto the surface of the substrate so that the energybeam “scans” the surface of the substrate in a patterned fashion andremoves material from the surface of the substrate in accordance withthe type of structure to be created.

An additional object of the present invention is to provide an apparatusand method in which, during the “material transfer” mode of operation,the control unit moves a material carrier element into an interceptingpath with the energy beam. When the energy beam impinges on thedeposition layer on the material carrier element such causestransference of the material contained in the deposition layer to thesurface of the substrate and the material is deposited thereon in apatterned manner in accordance with the type of the structure to becreated.

It is still a further object of the present invention to provide anapparatus for fabrication of miniature structures created by equipmentwhich includes a source for the energetic beam, a substrate, a materialcarrier element having a deposition layer thereon, and a control unitwhich synchronously manipulates the material carrier element and theenergetic beam in accordance with the type of the structure to becreated and the type of operation (additive or subtractive) to beperformed. In carrying out an additive process, the material carrierelement is displaced into interception with the energy beam, and therelative disposition between the energy beam and the substrate ischanged in a patterned fashion. In carrying out a subtractive process,the material carrier element is displaced away from interception withthe energy beam, and the relative disposition between the energy beamand the substrate is controlled in a patterned fashion.

In accordance with the present invention, an apparatus for fabricationof miniature structures includes a substrate, a source of energy capableof generating an energetic beam directed towards the substrate, amaterial carrier element displaceably disposed in a gap formed betweenthe source of energy and the substrate, a deposition layer supported onthe surface of the material carrier element facing the substrate, and acontrol unit operatively coupled to the source of energy (and/or to thesubstrate) for regulating parameters of the energy or energetic beam.The control unit controls the relative interposition between the energybeam and the substrate in accordance with a predetermined pattern. Thecontrol unit is also operatively coupled to the material carrier elementfor manipulating the same within the gap formed between the source ofenergy and the substrate by moving the material carrier element eitherinto a position corresponding to the “material removal” mode ofoperation or to a position corresponding to the “material transfer” modeof operation.

In the position corresponding to the “material removal” mode ofoperation, the material carrier element is displaced away fromintercepting the energy beam, in order that the energy beam has a directaccess or clear path to the substrate and impinges upon the surface ofthe substrate at a predetermined location. This causes disintegration ofthe material of the surface of the substrate to a predetermined depthand subsequent removal of the material from the predetermined locationon the substrate.

When the material carrier element is in the “material transfer” mode ofoperation, the material carrier element intercepts the energy beam whichimpinges upon the material carrier element, thus causing modification ofthe deposition layer at a predetermined location or point ofimpingement. The material contained in the deposition layer is thentransferred from the material carrier element to the substrate fordeposition thereon in accordance with a predetermined pattern.

In order to remove material from the substrate or to deposit materialonto the substrate, the control mechanism performs control of the sourceof the energy beam by changing relative disposition of the energy beamwith respect to the substrate, by regulating size and shape of thecross-section of the energy beam, and by regulating a fluence ormovement of the energy beam.

Although different energy beams may be used in the apparatus of thepresent invention such as laser beams, ion beams, and electron beams, apulsed UV excimer laser is thought to be preferred among others.

Preferably, the deposition layer on the material carrier elementincludes a material to be deposited (powder, metal, composite, alloy,ceramic, etc.), and/or a vaporizable substance.

Further, the present invention includes a method for fabrication ofminiature structures, which includes the steps of:

providing a fabrication tool which carries out both additive andsubtractive processes. The apparatus includes a substrate, acontrollable energetic beam directed towards the substrate, a depositionlayer supported on a material carrier element, and a control unitoperating the fabrication tool in either a “material removal” and/or a“material transfer” modes of operation. In the “material removal” modeof operation, the control unit displaces the material carrier elementaway from intercepting the energy beam and controllably changes therelative position between the energy beam and the substrate, therebyremoving disintegratable material from the surface of the substrate inaccordance with a predetermined pattern.

In the “material transfer” mode of operation, the control unit maintainsthe material carrier element in an interception path with the energybeam and controllably changes the relative position between the energybeam and the substrate, thereby transferring material contained in thedeposition layer onto the substrate for deposition thereon in accordancewith a predetermined pattern.

The “material removal” mode of operation may then be further initiatedafter the “material transfer” mode of operation for cutting thesubstrate into separate units with each having a created structurethereon and trimming the structures to required dimensions. In cleaningthe surface of the substrate before the Direct Write process isperformed, the “material removal” mode of operation is initiated priorto the “material transfer” mode of operation.

In the “material removal” mode of operation, electrical vias,micromachined channels, guides, and other contours may be created. Inthe “material transfer” mode of operation, a variety of electricalcomponents, such as semiconductor chips, sensors, detectors, and othercomponents, may be fabricated.

These and other novel features and advantages of this invention will befully understood from the following detailed description of theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of the operational principles ofthe apparatus for fabrication of miniature structures of the presentinvention;

FIG. 2A is a schematic representation of the “material transfer” mode ofoperation of the apparatus for fabrication of miniature structures ofthe present invention;

FIG. 2B is a schematic representation of the “material removal” mode ofoperation of the apparatus for fabrication of miniature structures ofthe present invention;

FIG. 3 is an overall block diagram of the apparatus of the presentinvention;

FIG. 4 is a block diagram of a controller subsystem of the apparatus ofthe present invention coordinating the substrate motion and laseractivation-deactivation;

FIG. 5 is a block diagram of a controller subsystem for laser motion andlaser actuation-deactuation control of the apparatus of the presentinvention;

FIG. 6 is a block diagram of the beam control subsystem of the apparatusof the present invention; and

FIG. 7 is a flow chart diagram of the computer system operation of thecontrol unit of the apparatus of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-6, the apparatus 10 of the present invention forfabrication of miniature structures includes a substrate 11, a source ofenergy 12 capable of generating an energy or energetic beam 13, amaterial carrier element 14 displaceably disposed in a gap 15 formedbetween the source of energy 12 and the substrate 11, a deposition layer16 supported on the backing material 17 of the material carrier element14, and a control unit 18 operatively coupled to the source of energy 12through the communication link 19 and to the material carrier element 14through the communication link 20. Alternatively, the control unit 18may be operatively coupled to the substrate 11.

Through the communication link 19, the control unit 18 actuates thesource of energy 12 to generate the energy beam 13, regulates theparameters of the energy beam 13 such as fluence, shape and size of thespot (cross-section of the beam), as well as changes relative positionbetween the energetic beam and the substrate in a patterned fashion.

In this manner, the control unit 18 “scans” the beam 13 over the surfaceof the substrate 11 either by moving the source of energy 12 in X-Ydirection shown by arrows 21, or by changing angular relativedisposition of the energy beam 13 with regard to the substrate 11 in apatterned fashion. In order to change a relative disposition between theenergy beam 13 and the substrate 11, the control unit 18 can,alternatively, move the substrate relative to the immovable beam 13.

In order to provide the control unit 18 with the function ofmanipulating the energetic beam 13, the communication link 19 includes amechanism 22 (best shown in FIGS. 1, 3 and 5) translating the electricalsignal transmitted from the control unit 18 into mechanical displacementof the source of energy 12 as well as monitoring a position of thesource of energy 12.

Through the communication link 20, the control unit 18 is capable ofmanipulating the material carrier element 14 within the gap 15 along thedirections shown by the arrows 23 so that the material carrier element14 may be displaced either away from the interception with the energybeam 13, or to the position intercepting the beam 13.

A mechanical displacement unit 24 is included in the communication link20 to translate the signal generated by the control unit 18 into themechanical displacement of the material carrier element 14 along thedirections shown by the arrows 23.

As best shown in FIGS. 1 and 4, the control unit 18 communicates withthe substrate 11 through a communication link 50. A substrate motionmechanism 51 is included into the communication link 50 for mechanicallydisplacing the substrate 11 according to a prescribed path and formonitoring the substrate position (as will be described in detail infurther paragraphs).

The control unit 18 operates the apparatus 10 of the present inventionin two modes of operation: “material removal” mode of operation and“material transfer” mode of operation. As best shown in FIG. 2A, in the“material” transfer mode of operation, the control unit 18 maintains thematerial carrier element 14 in an intercepting path with the energy beam13 and changes the relative disposition of the source of energy 12,i.e., the beam 13, with respect to the substrate in a patterned manner.In this manner, the energy beam 13 impinges upon the material carrierelement 14 at the surface 25 and causes modification of the depositionlayer 16 at predetermined spots or locations 26 from which materialcontained in the deposition layer 16 is deposited onto the surface 27 ofthe substrate 11 in a predetermined patterned fashion to form depositedstructures 28. The location of the islands (deposited structures) 28substantially corresponds to positions of the predetermined spots 26 ofthe deposition layer 16.

If deposition of a material different from that contained in thedeposition layer 16 is required for the fabrication of the miniaturestructures, another deposition layer on a material carrier element 14may be introduced into the gap 15 and the deposition process, i.e.,“material transfer” repeated.

For the sake of clarity, the process of the present invention isdescribed with a single material carrier element 14 and with the singledeposition step carried out during the “material transfer” mode ofoperation, although a plurality of material carrier elements 14 withdifferent deposition layers 16 may be used. A plurality of depositionsteps may also be sequentially performed in the apparatus in accordancewith the techniques described in the present invention.

As shown in FIG. 2A, the substrate 11 may have on the surface 27thereof, a prior deposited island 29 created either in the previouslyperformed “material transfer” mode of operation, or created by someother technique known to those skilled in the art.

When the additive step, i.e., “material transfer” has been performed,the control unit 18 changes the mode of operation to the “materialremoval” mode, shown in FIG. 2B. In the “material removal” mode ofoperation, a subtractive process takes place in which the control unit18 removes the material carrier element from an intercepting path of theenergy beam 13 in order to allow the energy beam 13 to directly impingeon the surface 27 of the substrate 11 in a patterned manner. Whenneeded, in accordance with the type of miniature structures to bemanufactured, the prior deposited island 29, as well as the depositedstructure 32 may be machined.

The “material removal” and “material transfer” modes of operation can beperformed in different sequences. For example, the material removal modeof operation may be performed first to ablate and clean the surface 27of the substrate 11 before any deposition step is performed. After thesurface 27 is prepared in a patterned fashion, the control unit 18 setsthe “material transfer” mode of operation, and the deposition step takesplace.

Alternatively, the “material transfer” mode of operation may beperformed initially so that deposited structures 28 and 32 are createdon the surface 27 of the substrate 11 and then “material removal” modeof operation is performed for different purposes, i.e., to machine thesurfaces of the structures 29 and 32, to make micromachined through vias30, or different channels and guides 31. Additionally, the substrate 11may be separated into separate units, each having one or severaldeposited structures 28, 29, and 32, depending on the type of theminiature structure to be manufactured.

In the apparatus 10 of the present invention, the source of energy 12 isa source of patterned energy which is capable of generating an energeticbeam such as ion beam, electron beam, or a laser beam capable ofpatterned displacement with relation to the substrate 11. The laser maybe an ultraviolet laser, such as an excimer laser, which may be pulsedpreferably at a rate about 10 Hz with a pulse width shorter than 10μsec.

The penetration of UV lasers is generally very shallow with respect tomost materials (approximately 500 angstroms) and is extremely useful forsurface annealing and sintering of particle composites as well assurface pre-treatment and cleaning.

If the energy beam is a UV laser beam, then the modifiable materialcarrier element 14 is formed of a material composition which istransparent to the ultraviolet radiation in order to allow the patternedenergy to reach either a deposition layer 16 on the material carrierelement 14 or the substrate 11 subject to the positioning of the element14. The deposition layer 16 may include materials to be deposited suchas powders, metals, composites, alloys, ceramics, and a vaporizablesubstance which may also include a binder, a molecular precursor, and/ora solvent. The vaporizable substance rapidly decomposes when exposed tothe energy beam 13 to propel the other constituents on the depositionmaterial to the substrate 11.

Powders of the deposition layer 16 may be formed of a distribution ofpowder sizes to form a closely packed matrix. Molecular precursorscontained in the deposition layer may react to reduce the externallygenerated densification energy (thermal or optical) or have anexothermic reaction when activated from the patterned energy source.

The uniqueness of the apparatus of the present invention is the use ofdirect write and laser micromachining capabilities with a minorperturbation of inserting and manipulating the material carrier element14 into the gap 15 formed between the source of energy 12 and thesubstrate 11. Thus, the apparatus of the present invention has all thecapabilities of depositing systems and of laser micromachining systems,so that the apparatus 10 can drill holes for vias, ablate and patternsubstrates, clean and anneal the surfaces of substrates as well asdeposited films.

The apparatus and method of the present invention allows rapid switchingbetween the “material transfer” and “material removal” modes ofoperation that is particularly important in a large scale direct writtencircuits. With an in situ laser micromachining capability, individualdevices can be written and trimmed as necessary to meet rigidspecifications of advanced technologies. The apparatus and method of thepresent invention is applicable to a wide range of materials, and isbuilt on well-established foundation of laser micromachining which iscomputer controlled and CAD/CAM compatible.

The system has a controlled environment, including a controlledatmosphere (oxidizing, reducing, or inert), temperature and pressure,and may be operated at ambient pressure and temperature. The combinationof controlled atmosphere and minimized time between pattern cleaning andsubsequent deposition greatly improves adhesion between the depositedmaterial and the surface 27 of the substrate 11. It also largely avoidsdamage to other structures which might result from the energy beamduring cleaning.

The technique and apparatus of the present invention can be used with arough preliminary alignment of the element in the system and may becarried out without registration marks. This is due to the fact that allthe fabrication which requires extremely accurate alignment isaccomplished without removing the substrate from the tool. As the systemuses both a patterned additive and subtractive process in a singlemachine, the product of the system of the present invention can bemechanical, electromechanical, sensor, electrical devices (resistors,capacitors, sensors, inductors, antennas, batteries, as well as a widevariety of electrical and electromechanical structures. Additionally,holes, vias, waveguides, registration marks, gratings, scribe lines,etching, trimming, and cleaning processes may be accomplished.

The present invention provides a unique implementation of both, anadditive and subtractive direct write processes in a single machine withthe ability to create complex circuits or structures in a conformalmanner on virtually any substrate. The additive process may be laserforward transfer (LFT) process, such as matrix assisted pulse laseroperation, or laser induced forward transfer (LIFT) process.

In the subtractive mode (“material removal” mode of operation) theapparatus 10 may act as a micromachining workstation, utilizing laserenergy to ablate, evaporate, melt, cut, drill, or otherwise removematerial from the workpiece. LFT deposited or otherwise existingstructures can be trimmed or shaped to precise dimensional values. Inthe writing mode, the laser might expose positive or negative resist,epoxies, or other sensitive materials in complex patterns with highspatial resolution. Such a capability permits stereolithographicfabrication of three-dimensional structures. In total, the apparatus andthe technique of the present invention are easily and flexiblycustomized, robust, broad in choice of materials and substrate, anddeposition conditions, such as temperature, pressure, and cover gas.

The apparatus of the present invention has the modified or removablematerial carrier element 14 and thus possesses the ability to accomplishpattern tasks such as laser surface clean as well as direct deposit ofmetals, ceramics, polymers, and much more in situ, in air and at roomtemperature.

The spatial resolution of most LDW and LFT techniques is generallylimited by the obtainable laser spot size or shape and the precision ofthe motion system or beam steering mechanism. Using LFT, the Applicantshave demonstrated gold lines having a width less than 8 microns. Writtenfeatures have been subsequently trimmed with single micron precision.

By adjustment of the laser spot size and/or shape, the size and shape ofthe written features may be varied. For example, a 10 micron wideconducting line may be written followed by a 50 micron contact padwithout any tool change. The apparatus of the present invention has thepotential to obtain write speeds of meters per second while exactingposition tolerances to approximately one micron. Mechanical techniquessuch as Micropen or inkjet cannot match this combination of speed andprecision.

The apparatus of the present invention allows for a wide scope ofmaterials to be deposited including materials that are completelyinsoluble. Very high or very low melting materials, metals, oxides,ferrites, even sensitive polymers are applicable using this technique.

During the process of making a miniature structure in the fabricationtool of the present invention, the control unit 18 controllably changesthe relative position between the energy beam 13 and the substrate 11 toremove a pattern of removable material from the surface of thesubstrate; and then without removing the substrate from the tool,controllably changes the relative position between the energy beam 13and the substrate 11 to transfer a pattern of depositable material tothe substrate 11.

The modifiable material carrier element 14 which supports the depositionlayer 16 is capable of being displaced from intercepting the beam 13thus allowing the beam 13 to pass to the substrate 11 without affectingthe relative position between the energy beam 13 and the substrate 11.The relative position between the substrate 11 and the beam 13 iscontrolled by the patterning device (the control unit 18) and alignmentis unaffected by changing the mode of operation (“material removal” and“material transfer” modes of operation). Since both operations areaccomplished in a single machine the substrate 11 remains in place andpossible problems, such as misalignment, contamination, or damage whichresult from removing a substrate from a tool, are avoided.

The short absorption depths in most materials and the small minimum spotor feature size (proportional to the wavelength) give ultraviolet lasersmany advantages for both LFT and laser machining processes. Most resistsand optically cured epoxies rely on UV exposures as well. The combinedcapability to exploit all of these technologies are inherent in thedesign of the machine.

In the apparatus of the present invention, and in accordance with theprinciples and technique of the present invention, the resistors createdon the surface of the substrate can be trimmed to value, RF filternetworks tuned, and defects, such as shorts, may be removed.

By sliding the material carrier element away from interception with thelaser beam and by adjusting the UV laser fluence to approximately 1J/CM² or greater, the apparatus 10 is transformed into a machine whosefunction is essentially the opposite of the direct write technologyprocess, i.e., a micromachining workstation. Vias through the substratecan be drilled with micron precision. Channels for positioning externalcontacts or laying subsurfaces components can be excavated with ease.Microfluidic structures, functioning as chemical sensors or biologicalagent detectors, can be embedded directly in the same substrate. Bydecreasing spot fluence to approximately 100 MJ/CM² or less, theablation rate will drop to zero but may still be more than sufficient toexpose the sensitive materials.

The “material removal” and “material transfer” modes of operation canchange between different materials as quickly as the materials carrierelements are mechanically translated into the optical path. Theapparatus of the present invention uses an optically based approach, andthus it lends itself to several in situ optical diagnostics, e.g.,ellipsometry, FTIR, optical pyrometry, etc.

The advantages of the fabrication technique of the present inventionhave been attained due to the design of the apparatus 10, andparticularly due to a functional performance and operational approach ofthe control unit 18, best shown in FIGS. 3-7. The control unit 18coordinates all aspects of deposition/ablation process;

provides interfacing for an operator control and monitoring;

monitors all critical subsystems (including optical systems) of theapparatus 10 for quality control and safety;

provides communication with external systems and data bases, bothinternal and external; and

provides for compatibility with CAD/CAM control.

Referring to FIG. 3, showing the overall block diagram of the system ofthe present invention, the control unit 18 includes a main computer 52,motion/laser controller 53, substrate environment controller 54, and abeam controller 55. The main computer 52 interchanges data with thesubstrate environment controller 54 through bi-directional channel 56,and with the motion/laser controller 53 through the bi-directionalcommunication channel 57.

The motion/laser controller 53, is external or internal to the maincomputer 52, provides accurate (approximately 1 micron) dynamic closedloop position control of the substrate, material carrier elementposition, and scanning laser beam. The motion-laser controller 53 movessubstrate with high speed (up to 1 meter per second) and accuracy(approximately 1 micron) as well as provides for smoothness of travelfor patterned deposition of ablating micromachining. Also, the maincomputer 52 communicates with the beam controller 55 through thebi-directional communication channel 58.

The substrate environment controller 54 is bi-directionally coupledthrough the communication link 59 to a substrate fixture 60 supportingthe substrate 11 thereon. The substrate fixture 60 along with substrateenvironment controller 54 provides for holding the substrate reliably,keeps it at required level, controls its temperature as well asatmosphere. The fixture 60 includes a temperature control heater block61 which is controlled in a closed loop fashion by the substrateenvironment controller 54 for controlling deposition conditions of thesystem 10.

The fixture 60 includes stages 62 and 63, best shown in FIGS. 1 and 4,which being controlled by the motion/laser controller 53, provide for arequired displacement of the substrate 11 in accordance to a prescribedpath, as will be described in detail in further paragraphs withreference to FIG. 4. For controlling and monitoring the displacement andposition of the substrate 11, the bi-directional communication link 50operatively couples the stages 62 and 63 of the substrate fixture 60with the motion/laser controller 53 to convey control signals to thefixture 60 and readings of the position to the motion/laser controller53.

The motion/laser controller 53 further communicates with the materialcarrier element 14 through the bi-directional communication channel 20which has included therein the mechanism 24 responsible for mechanicaldisplacement of the material carrier element 14 either into interceptingposition with the laser beam 13 (in the “material transfer” mode ofoperation) or away from interception with the laser beam 13 (in the“material removal” mode of operation). The mechanism 24 also changes aposition of the material carrier element with regard to the laser beam13 according to the prescribed path for attaining the effectiveutilization of the depositable material of the deposition layer 16,deposition of a specific depositable material contained in thedeposition layer 16, and deposition of the depositable material on anaimed area of the substrate 11. Depending on the type of the materialcarrier element 14, the mechanism 24 has a distinctive design featuresadapted for the particular type of the material carrier element, butwhich in any event, mechanically displaces the material carrier element14 as prescribed by the motion/laser controller 53 through the channel20. The mechanism 24 may include “reel-to-reel” mechanism,spinning-sliding vacuum system, or other motion actuating mechanisms.

The control unit 18, as can be seen in FIG. 3, is operatively coupled tothe laser system 12 through the communication channel 19 which includesthe communication channel 58 for providing coupling between the maincomputer 52 and the beam controller 55, and the communication channel 64for providing a bi-directional coupling between the motion/lasercontroller 53 and the laser 12, as will be described in detail furtherwith reference to FIGS. 5 and 6.

The laser 12 provides focusable pulsed energy source serving to:

transfer material from the deposition layer 16 to the substrate 11 inthe “material transfer” mode of operation;

ablatively remove the material from the surface of the substrate 11 inthe “material removal” mode of operation;

remove foreign material from the substrate and/or prepare and activatethe substrate surface before or after deposition in the “materialremoval” mode of operation, particularly “cleaning” mode of operation;and

shape and refine deposited or existing structures to desired dimensionsor values in the “material removal” mode of operation, particularly“laser trimming” mode of operation.

As discussed in the previous paragraphs, the ultraviolet pulsed laser ispreferred due to superior ablation characteristics for many materials.Specifically, all solid state frequency tripled neodymium vanadatelasers (radiating at approximately 355 nm), and frequency quadrupledenergy laser (radiating approximately at 266 nm) are preferred becausethey offer high repetition rates, short pulses, sufficient beam quality,high average power, and superior reliability at low maintenance. Thelaser beam 13 generated by the laser 12, is controlled by the beamcontroller 55 under the overall control and monitoring of the maincomputer 52. As disclosed in previous paragraphs, the beam control isembedded in the system 10 of the present invention in order to deliverthe laser beam of the desired optimal laser spot size, shape, andfluence to the material carrier element 14 or to the surface of thesubstrate 11. Beam shape and size determines the resolution and patternof the deposition or ablation. Once the shape, size and fluence of thelaser beam 13 has been attained, the laser beam impinges upon thesplitter 65 whereat the laser beam 13 splits into a beam 66 directed tothe objective 67 which further focuses the beam 66 and directs the sameto either the surface of the material carrier element 14 or to thesurface of the substrate 11. The mirror splitter 65 is a highlyreflective at laser wavelength but transparent for invisible spectrumfor the video system 69. Another portion of the laser beam 13,particularly the beam 68, is directed by the splitter 65 to a videosystem 69 which includes a video microscope/video camera 70 and a videomonitor 71, best shown in FIG. 5. The signal from the videomicroscope/video camera 70 is supplied through the line 72 to a machinevision system 72 for image capture and processing. The videosystem/machine vision system permits an operator to accurately positionsubstrate for registration and scaling with existing pattern;

to measure and inspect the substrate; and

to facilitate leveling, focusing and displacement of the substrate andthe objective 67 in the direction shown by arrows 73 and 74. The opticalsubsystem of the apparatus 10 of the present invention which includesthe video system 69, video microscope/video camera 70, video monitor 71,and the machine vision system 72 is a well-known machine visiontechnique and is not intended to be described herein in further detail.The data from the machine vision system 72 are transmitted to the maincomputer 52 for storing, further processing, and for communication withthe motion/laser controller 53 through the communication channel 57 forfurther control of the relative disposition between the elements of thesystem 10, as well as actuation-deactuation of the laser 12.

Referring now to FIG. 4, showing a block diagram of the substratemotion/laser controller 53 for substrate motion and laseractivation-deactivation control, the motion/laser controller 53, eitherexternal or internal to the main computer 52, provides accurate(approximately 1 micron) dynamic closed loop position control of thesubstrate. In this manner, the controller 53 monitors real time positionof the substrate and coordinates the same with generating of laserpulses so that the laser pulses can be triggered with very highalignment accuracy.

It is clear that if the laser beam is delivered at constant repetitionrate to either the material carrier element, or the substrate, thepulses tend to “pile up” during acceleration and deceleration of thestages 62, 63, or mechanical displacement mechanism 24, or laser beamdisplacement mechanism (to be discussed further in detail with thereference to FIG. 5) and makes deposition and ablation depth controldifficult. To obviate these unwanted phenomena, the actuation of thelaser is to be coordinated with deposition of the substrate, laser beam,and/or material carrier element in real time fashion. As best shown inFIG. 4, the main computer 52, through the motion-laser controller 53,transmits signals representative of a prescribed path (received from the“Design Concept” block 75 of the FIG. 3) which is a CAD/CAM developeddesign concept for layout of miniature structures on the substrate ormicromachining layout) is supplied to the motion control board 77 via achannel 78. The motion control board 77 in accordance with theprescribed path controls an X-motor 79 and a Y-motor 80 to force thestages 62 and 63 carrying the substrate 11 to move the same in requireddirection a required distance. At the same time, an X-encoder 81 iscoupled to the X-stage 62, and the Y-encoder 82 is coupled to theY-stage 63 for measuring X and Y displacements of the stages 62, 63 andtranslating them into the format understood by the motor control board77 and the processing block 83. The data from X-encoder 81 and Y-encoder82 are supplied through the channels 84 and 85, respectively to themotion control board for being processed and used for generating variouscontrol signals outputted through outputs 86. These control signals maybe further transmitted to the optical system of the laser forcontrolling the laser shutters, laser optical zoom, aperture selection,etc.

Simultaneously, the data corresponding to X and Y displacements of thestages 62 and 63 are transmitted from the X-encoder 81 and Y-encoder 82through the communication links 87 and 88, respectively, to theprocessing block 83 wherein the X and Y displacements are processed andcalculated according to the formula$\left( \frac{X^{2} + Y^{2}}{m} \right),$

wherein X is a displacement of the stage 62, Y is a displacement of thestage 63 and m is an integer defining the number of pulses for eachdisplacement vector. The data from the processing block 83 is outputthrough the channel 89 to a “distance—to pulse out” converter 90. Theconverter 90 thus receives vector displacement increment and in responsethereto, generates trigger pulse which is transmitted to the laser 12through the line 91 for actuating-deactuating the laser 12. Thus, thelaser 12 generates laser beam 13 once a required displacement of thesubstrate 11 has been attained. The “distance-to-pulse out” converter 90is a converter manufactured by Aerotech, Inc. for operation of the knownmicromachining stations.

As was described in previous paragraphs, change of the relativedisposition between the laser beam, substrate and/or material carrierelement, may be implemented in following three fashions:

movement of the substrate with respect to the immovable laser beam;scanning of the laser beam with regard to the substrate and/or materialcarrier element; and combinatorial motion of the substrate and the laserbeam. Thus, when scanning of the laser beam with respect to thesubstrate and/or material carrier element is chosen for operation, thesystem 10 of the present invention will operate in accordance with FIG.5, illustrating the motion/laser controller 53, particularly, asubsystem thereof for laser motion and laser actuation-deactuationcontrol.

As shown in FIG. 5, data representative of the prescribed path 76 aresupplied to the motion control board 92 (which may coincide with themotion control board 77). The motion control board 92, in the mannerdescribed with respect to FIG. 4, transmits control signals over theline 94, either to the optical system of the laser 12 or to mechanicalstages carrying the laser 12 for displacement of the laser beamgenerated by the laser 12, thus providing scanning of the laser beamover the surface of the material carrier element 14 or the substrate 11.

X and Y encoders 95 and 96, or other mechanisms sensing displacement ofthe scanning laser beam receive information from the “opticalsystem/stages” 93 of the laser 12 and transmit this information to aprocessing block 97 which processes the information received from theencoder 95, 96 either in the same manner as the processing block 83 ofFIG. 4, or in any other fashion known to those skilled in the art andthen outputs the data representative of the displacement of the laserbeam through the line 98 to the “distance-to-pulse out” converter 99which in a well-known manner converts the data representative of thedisplacement of the scanning laser beam into the controlling triggerpulses which are supplied to the laser 12 through the line 100 foractuating/deactuating the laser 12.

The generated laser beam 13 is further controlled by the beam controller55 and is further directed to the material carrier element 14 or thesubstrate 11 as described in the previous paragraphs. In this manner,the firing of the laser beam will be coordinated in precise fashion withthe scanning of the laser beam with regard to the substrate 11 or thematerial carrier element 14.

Referring to FIG. 6, the beam controller 55 facilitates the delivery ofthe laser beam of the desired optimal laser spot size, shape, andfluence to the substrate or to the material carrier element. The beamcontroller 55 includes an acousto-optic modulator 101 coupled to thelaser 12 to provide a convenient and efficient mode to rapidly (fasterthan 100 ms) shutter the laser “on” or “off” as well as to control theenergy of the individual generated laser pulses dynamically. Theacousto-optic modulator 101 external to the laser cavity allows thelaser to run at constant repetition rate for maximum stability.Throughput efficiency of the acousto-optic modulator can be controlledby the motion/laser controller 53 in the range between 0% to more than90%.

A beam shaping optical system 102 is coupled to the acousto-opticmodulator 101 to control size and shape of the laser beam at the target.The beam shaping optics 102 25 includes an optical zoom shaped aperturearray, and/or diffracted optic beam shaper.

The control of the power and generation of the laser beam is animportant feature since fluences of the generated laser beam are to bemaintained at different levels for different purposes. As an example fordeposition, an optimal fluence is kept usually in the range of 0.2-2.0J/Cm² per pulse. For ablation micromachining, generally high fluencesare desired for maximum speed and efficiency, typically approximately1-100 J/CM² per pulse. Lower fluences, approximately 0.2-2.0 J/CM² canbe used for precise depth control. Using the structure of the system ofthe present invention, sub-micron depth control has been demonstrated.

The laser beam having the required fluence (provided by theacousto-optical modulator 101) and required size and shape (provided bythe beam shaping optics 102) is further output to the splitter 65 forfurther displacement to the target (material carrier elements 14 or thesubstrate 11) through the objective 67. The objective 67 is provided forfinal imaging of the UV laser beam and video magnification. Theobjective 67 is mounted on a focusing stage providing displacement inthe direction shown by arrows 73 to permit proper imaging regardless ofthe substrate height, regardless of whether the material carrier elementis in the beam path.

A detector 103 monitors laser pulse energy and supplies datarepresentative of the real time laser beam energy to the control unit 18for closed loop control.

Referring to FIG. 7, showing a block diagram of the computer operationalprinciples of the control unit of the apparatus of the presentinvention, the flow chart is initiated in block 110 corresponding to thepre-start-up procedure which includes alignment of the elements(substrate, material carrier element, laser beam) of the system,registration and positioning. Initially, the material carrier element ismaintained in interception position with the laser.

From the block 110, the signal logic is directed to decision block 112“Deposition or subtraction mode?” If a subtraction (“material removal”mode of operation) is chosen, the logic moves to the block 114 “Removematerial carrier element from the beam path”. In accordance with thecommand of the block 114, the control unit 18 then outputs a controlsignal to mechanism 24, best shown in FIG. 3, for displacing thematerial carrier element 14 away from the interception position with thelaser beam 13.

From the block 114, the logic moves to the block 116 “Translatesubstrate (or beam) along path”.

If in the logic block 112, the deposition (“material transfer” mode ofoperation) has been chosen, the logic moves again to the block 116. Thelogic block 116 receives a desired pattern path which corresponds to theprescribed path 76 best shown in FIGS. 3-5. Thus, upon receiving thedesired pattern path, the logic block 116 changes relative dispositionbetween the substrate and the beam in accordance with the prescribedpath.

From the block 116, the flow chart moves to the decision block 118 “Firelaser at current location?”. If the laser is to be fired, i.e., theanswer is “Yes”, the logic moves to the block 120 “Admitcontrolled-energy laser pulse”. At this time, the motion/lasercontroller 53, as best shown in FIGS. 3-5, “commands” the laser 12 togenerate a laser pulse which impinges at a predetermined area of thesubstrate 11 (in the “material removal” mode of operation), or thematerial carrier element 14 (in the “material transfer” mode ofoperation). After the laser beam modifies either the deposition layer 15of the material carrier element 14 or the surface of the substrate 11,the signal is directed to the logic block 122 “Increment materialscarrier position (deposition mode)”. In this instance, the control unit18 deactuates the laser 12, thus seizing the laser beam, and moves thematerial carrier element 14 to the next position according to theprescribed path 76 if the apparatus 10 operates in the “materialstransfer” mode of operation.

If however the apparatus 10 operates in the “material removal” mode ofoperation, the control unit 18 seizes or captures the laser beam andmoves the substrate to the next position in accordance with theprescribed path 76. Thus, from the logic block 122, the flow chartreturns to the logic block 116, where the translation of the substrate(or the laser beam) is performed along with prescribed path 76.

If however the answer to the logic block 118 is “No”, meaning that thelaser is not to be fired at a current location of the substrate or thelaser beam, the logic flows to the decision block 124 “All PathsComplete?”. If the answer is “Yes”, the logic flows to the “EndProcedure” block 126.

If however, in the logic block 124, it has been decided that not allprescribed paths have been yet completed, i.e., the answer is “No”, thelogic returns to the block 116 to translate the substrate (or the laserbeam) along the prescribed path 76 for further leading the flow charteither along the loop comprised of logic blocks 118, 120, 122 and 116;or sequentially along the loop comprised of the logic blocks 118, 124,116.

Known material compositions used in this invention which are transparentto laser beams include fuse silica, borosilicate glass, polyester filmssuch as Mylar, acrylic, as well as a wide variety of other compositionsknown in the art.

Although this invention has been described in connection with specificforms and embodiments thereof, it will be appreciated that variousmodifications other than those discussed above may be resorted towithout departing from the spirit or scope of the invention. Forexample, equivalent elements may be substituted for those specificallyshown and described, certain features may be used independently of otherfeatures, and in certain cases, particular locations of elements may bereversed or interposed, all without departing from the spirit or scopeof the invention as defined in the appended Claims.

What is claimed is:
 1. A method for fabrication of miniature structures,comprising the steps of: (a) providing a fabrication tool, including: asubstrate, a controllable energetic beam directed towards saidsubstrate, a deposition layer supported on a material carrier element,and control means operating said fabrication tool in either a materialremoval and material transfer mode of operation; (b) displacing saidmaterial carrier element away from intercepting with said energetic beamwhen said fabrication tool is in said material removal mode ofoperation, and controllably changing relative position between saidenergetic beam and said substrate, thereby removing a disintegratablematerial from the surface of said substrate in accordance with apredetermined pattern, and (c) maintaining said material carrier elementintercepted with said energetic beam when said fabrication tool is insaid material transfer mode of operation, and controllably changingrelative position between said energetic beam and said substrate,thereby transferring a material contained in said deposition layer ontosaid substrate for deposition thereon in a patterned fashion.
 2. Themethod of claim 1, wherein said energetic beam is a laser beam.
 3. Themethod of claim 1, further including the steps of: operatively couplingsaid control means to said energetic beam for regulating parameters ofsaid energetic beam, and for changing disposition of said energetic beamwith respect to said substrate.
 4. The method of claim 1, furtherincluding the steps of: operatively coupling said control means to saidmaterial carrier element for manipulating said material carrier elementin accordance with a required mode of operation of said fabricationtool.
 5. A method for fabrication of miniature structures, comprisingthe steps of: providing a substrate, providing a source of energycapable of generating an energetic beam, positioning a material carrierelement in a gap formed between said substrate and said source ofenergy, said material carrier element having a deposition layer on asurface thereof facing said substrate and containing a depositablematerial to be deposited onto said substrate, operatively coupling acontrol means to said material carrier element and to said source ofenergy, and synchronously controlling said material carrier element andsaid source of energy in accordance with a miniature structures to befabricated in either a material removal mode of operation or a materialtransfer mode of operation, displacing said material carrier element tosaid first position thereof external to an intercepting path with saidenergetic beam, and thereby allowing a direct access of said energeticbeam to said substrate, and thereby causing disintegration in apatterned manner and to a predetermined depth thereof of the material onthe surface of said substrate, and further displacing said materialcarrier element to said second position for interception with saidenergetic beam path, thereby causing modification of said depositionlayer at a predetermined location and transferring the materialcontained in said deposition layer onto said substrate to be depositedat a predetermined area thereof when in said material transfer mode ofoperation.
 6. The method of claim 5, further including the steps of:generating said energetic beam, forwarding said energetic beam in adirection towards said substrate, displacing said material carrierelement to a first position thereof in said gap corresponding to saidmaterial removal mode of operation, displacing said material carrierelement to a second position thereof in said gap corresponding to saidmaterial transfer mode of operation, and in either of said materialtransfer and material removal modes of operation, controlling a relativeinterposition between said energetic beam and said substrate inaccordance with a predetermined pattern.
 7. The method of claim 5,further including the step of: creating an electrical via in saidsubstrate in said material removal mode of operation.
 8. The method ofclaim 5, further including the step of: forming a micromachined channelin said material removal mode of operation.
 9. The method of claim 5further including the steps of: depositing a material on the surface ofsaid substrate prior to said material removal mode of operation, anddisintegrating said priorly deposited material on the surface of saidsubstrate by said energetic beam according to a predetermined patternduring said material removal mode of operation.
 10. The method of claim5, further including the steps of regulating a size of the cross-sectionof said energetic beam.
 11. The method of claim 5, further including thesteps of regulating the shape of the cross-section of said energeticbeam.
 12. The method of claim 5, further including the step ofregulating the fluence of said energetic beam.
 13. The method of claim5, further including the step of pulsing said source of energy atpredetermined time intervals.